Glycerophospholipids such as phosphatidyl choline consist of glycerol esterified with two fatty acyl groups and one phosphate or esterified phosphate group. For some applications of the phospholipids it is desirable to exchange the acyl groups in the phospholipids, e. g. in order to improve their heat stability.
In this respect it was previously shown, e. g. in U.S. Pat. No. 5,314,706, that egg yolk fortified with exogenous lysophosphatidylcholine obtained by hydrolysis of lecithin with a phospholipase A2 improved the thermostability of emulsions, particularly mayonnaise.
Furthermore, it was shown in WO 91/03564 that enzymatic interesterification of a phospholipid with a fatty acid using a lipase catalyst immobilized on a macroporous carrier in an organic solvent gave rise to improved incorporation of specific acyl moieties in the phospholipid. In that process, a large excess of fatty acid was used which remains in the reaction mixture at the end of the process and which is not easily separated from the desired modified lecithin.